Source

goimp /

1. Set GOROOT to the go/ directory and O to [568]
2. Create a pkg directory
3. Make sure goimp, goimps and gotypes are in your PATH
$ goimps pkg/
Generates types-interfaces and interfaces-types (it is damn slow)
The pkg/ directory will contain executables to print the interfaces implemented by each type
$ goimp bytes Buffer
Shows the interfaces implemented by pkg.Type